As a general rule, German tank armament was always well in advance of
Allied developments. At a time when British tanks were armed with the 2 pr
gun, German tanks were being armed with 5 cm and 7.5 cm guns firing
4.56-and 14-pound projectiles respectively. But tank guns are not rated on
the weight of shot that they fire alone.

Shell Speed &
Performance
Another very important factor is the speed at which the shot or shell
(shot is solid metal, and shell contains a high explosive charge) leaves
the muzzle of the gun. This is usually referred to as the muzzle velocity
or V0. Here again, the Germans were usually well in advance of Allied gun
designers, and in the two 8.8 cm guns that were produced for tanks, they
were able to combine a high muzzle velocity and shot weight that could
outrange and destroy almost any Allied counterpart.

The most usual way to increase the muzzle velocity of a gun is to increase
the charge in the propelling cartridge, but this places severe strain on
the breech mechanism and recoil system. Another method, often employed by
German designers, was to increase the length of the barrel. The 7.5 cm gun
used on the PzKpfw IV was increased from L/24 to L/43 and eventually to
L/48, and each increase in length brought about an increase in the hitting
power of the gun. But an increase in barrel length also brought about
severe strain on the recoil mechanism, which was usually minimised by the
use of a muzzle brake that could reduce recoil forces by directing a
proportion of the muzzle blast to the rear at the time the shell left the
barrel.

Tank Machine Guns
Starting at the bottom of the scale, all German tanks mounted at least one
machine-gun. The standard German calibre for machine-guns was 7.92 mm
(0.312 in). The most widely used machine-gun fitted to tanks was the MG34,
a Rheinmetall weapon which was at one time the standard German infantry
machine-gun. On tanks the MG34 was mounted co-axially with the main
armament and was often carried in a complex ball-mounting on the front
glacis plate. By the time the war ended most German tanks had an extra
machine-gun fitted on the commander's cupola for anti-aircraft use.

After about 1943, a new gun known as the MG42 began to be issued. This gun
was cheaper and simpler to produce than the MG34, and was designed to
replace the earlier gun, but events were such that production could not
keep pace with demand and the MG34 was still in use in 1945 as the war
ended.

Main Tank Gun
Going up the calibre scale, the next tank gun was the 20 mm KwK 30. This
was a shortened version of the 20 mm Flak 30 anti-aircraft gun. This
weapon was originally a Swiss Solothurn design known as the T5-150 or ST
9, and was developed under Rheinmetall guidance. It was used only on the
PzKpfw II and on some armoured cars. It was later supplemented by the
Mauser 20 mm KwK 38, which was again a shortened version of an
antiaircraft gun, in this case the 20 mm Flak 38. This gun used magazines
holding either ten or 20 rounds.

The 3.7 cm gun used on the early PzKpfw III was an L/45 weapon developed
from the 3.7 cm Pak 35/36 anti-tank gun. It was not produced in large
numbers after 1940.

Next in size came the 5 cm KwK L/42 which was fitted to the early PzKpfw
III Ausf E to H. This gun was well in advance of similar tank armament at
the time of its introduction to service, but was soon outclassed when it
encountered the thick hide of the Russian T-34 and KV-I. This had already
been anticipated by Hitler, who had ordered an increase in barrel length
to L/60, but production difficulties had prevented this order being
carried out.

Eventually the L/60 gun was placed in production as the 5 cm KwK 39, and
in performance was equal to the 5 cm Pak 38 anti-tank gun in use with
Wehrmacht anti-tank units.

The 7.5 cm KwK as originally fitted to the early models of the PzKpfw IV
was a low velocity gun firing HE shells. In its original form it was a
most effective gun when fired against contemporary tanks, but by the end
of 1940 it was realised that it had become ineffective against the heavy
armour of some Allied vehicles. It was replaced in service by the interim
7.5 cm KwK 40 with an L/43 barrel. The old L/24 guns that were replaced
were not scrapped but were placed in store, only to be withdrawn for use
in the late models of the PzKpfw III, and some were also placed on
half-tracks for close support duties.

The L/43 guns were soon replaced by the 7.5 cm KwK 40 with an L/48 barrel.
This gun was a development of the famous Rheinmetall 7.5 cm Pak 40
anti-tank gun and it was to prove itself one of the most potent and
effective of all the German tank guns. It was certainly the most widely
used for it was placed on a wide variety of tank destroyer chassis, and
one version ended up as an anti-tank gun mounted on aircraft (the 5 cm gun
also went airborne).

A further development of the 7.5 cm KwK 40 was the KwK 42 which had an
L/70 barrel. This gun was used on the Panther and was a considerable
advance as a tank gun on the KwK 40. Plans were in hand to increase this
weapon to an L/100 version but this project was dropped before the war
ended.

The first 8.8 cm tank gun was the KwK 36 which was fitted to the Tiger. It
was a powerful weapon with a considerable range but by 1944 it was
considered obsolescent and was replaced in production by the even more
powerful 8.8 cm KwK 43. The two guns were not related as the KwK 43 had a
larger and more powerful propelling charge, and the KwK 36 was an L/56 gun
while the KwK 43 had a barrel length of 71 calibres. In its latter form,
the KwK 43 can be considered to have been the best all-round tank gun in
use by any of the combatants involved in World War 2.

As the war ended, plans were well advanced on even heavier tank armament.
The 12.8 cm gun was intended for use in tank turrets, but under
development were smooth-bore guns firing finned projectiles, a High-Low
pressure gun, and various rocket-propelled projectiles which were intended
to have the tank-killing capacity of current anti-tank guns without the
weight or cost penalties involved. As the war ended, none of them were
sufficiently advanced for service use.